1. Field of the Invention
The present invention generally relates to a wireless communications system, particularly to a location search technique of searching a location of a portable device.
2. Description of the Related Art
In recent years, location detection systems using a global positioning systems (GPS), a radio local area network (LAN), a radio tag and the like have been developed. In fields of mobile communications systems such as a cellular phone and PHS, a location search system has been developed using radio waves from a base station (e.g., see Jpn. Pat. Appln. KOKAI Publication No. 10-221425).
A system for managing a location of a user having portable devices (data processing devices) such as the cellular phone and a personal digital assistant (PDA) on premises such as an office building of a company, a shopping center, or public facilities such as stations and hospitals has not been practically used.
To realize this system, simply the system for detecting a position of the portable device on the map (on the plane) is insufficient. Especially, a system is necessary which is capable of specifying a region where the user is positioned among regions such as rooms and passages existing every floor on the premises (sometimes referred to as a three-dimensional spatial range or simply the spatial range).